How planets grow in double-star systems has always held a particular fascination for me. The reason is probably obvious: In my younger days, when no exoplanets had been discovered, the question of what kind of planetary systems were possible around multiple stars was wide open. And there was Alpha Centauri in our southern skies, taunting us by its very presence. Could a life-laden planet be right next door? What Kedron Silsbee and Roman Rafikov have been working on extends well beyond Alpha Centauri, usefully enough, and helps us look into how binaries like Centauri A and B form planets. Says Rafikov (University of Cambridge), "A system like this would be the equivalent of a second Sun where Uranus is, which would have made our own solar system look very different." How true. In fact, imagining how different our system would work if we had a star among the outer planets raises wonderful questions. Could we have a habitable world around each star in such a binary? And if so, wouldn't...

The things we look for around other stars do not necessarily surprise us. I think most astronomers were thinking we'd find planets around a lot of stars when the Kepler mission began its work. The question was how many -- Kepler was to give us a statistical measurement on the planet population within its field of stars, and it succeeded brilliantly. These days it seems clear that we can find planets around most stars, in all kinds of sizes and orbits, as we continue to seek an Earth 2.0.. The continuing news about the star PDS 70, a young T Tauri star about 400 light years away in Centaurus, fits the same mold. Here we're talking not just about planets but their moons. No exomoons have been confirmed, but there seems no reason to assume we won't begin to find them -- surely the process of forming moons is as universal as that of planet formation. The interest is in the observation, how it is made, and what it implies about our ability to move forward in characterizing planetary...

The NEID spectrograph has passed the Operational Readiness Review necessary for final acceptance and regular operations. Developed by NASA and the National Science Foundation's NN-EXPLORE exoplanet science program, it has been put through a lengthy commissioning process in the five years since the radial velocity planet hunter design was selected. NEID is mounted on the WIYN 3.5m telescope at Kitt Peak National Observatory in Arizona, and we now have word that its scientific mission has begun. Image: Sunset over Kitt Peak National Observatory during NEID commissioning in January 2020. Credit: Paul Robertson. As a radial velocity instrument, NEID is all about the tugs one or more planets exert on the host star, as measured radially -- toward Earth, then away from it -- during the planets' orbits. The Doppler shift in the star's light contains the information. That these are exquisitely tiny measurements should be obvious. Jupiter induces a 13 meter per second wobble on our star, but...

300 light years from Earth in the constellation Musca, the gas giant TYC 8998-760-1 b, along with a companion planet, orbits an infant K-class star about 17 million years old. We're probably looking at a brown dwarf here rather than a gas giant like Jupiter, for TYC 8998-760-1 b is about 14 times Jupiter's mass, nudging into brown dwarf territory, and it appears to be roughly three times as large, unusual for brown dwarfs. The planet's separation from its host star is pegged at 160 AU. An inflated atmosphere due to processes still unknown? We don't know, but both this and the companion planet have been directly imaged. Now TYC 8998-760-1 b resurfaces through work with the European Southern Observatory's Very Large Telescope, as reported in the latest issue of Nature. Led by first author Yapeng Zhang (Leiden University, The Netherlands), the team of astronomers detected carbon isotopes in the object's atmosphere, showing higher than expected carbon-13 content. Here is the image, first...

Demonstrating once again the role amateurs can play in supporting ongoing observations, a new project linking NASA and the American Association of Variable Star Observers is being launched. Exoplanet Watch isn't about discovering new transiting planets (although the potential is there) as much as tightening up the information we already have about planets currently under investigation. The idea is to help professional observers know when to look, which allows them to maximize precious observing time on instruments that are always in high demand. Transit timing is the key, and the fact is that for many known exoplanets, knowing exactly when to look is problematic. Rob Zellem (JPL) is project lead for Exoplanet Watch: "If there's a 15-minute under-estimate of when a transit will occur, that's an extra 15 minutes I have to build into my observing scenario. Time on big telescopes, especially space telescopes, is very, very precious. If you're observing a lot of planets, [15 minutes]...

Many of the planet-hosting stars being identified by TESS, the Transiting Exoplanet Survey Satellite, may actually be binaries. Unless examined closely, a pair of stars can appear as a single object, requiring high resolution instrumentation to separate into its component parts. As it applies to exoplanet research, this is a problem, for TESS operates by the transit method, tracking the change in a star’s light curve as a planet crosses the face of the star. Light curves yield precious information, but the presence of a second star unknown to researchers can obscure smaller, rocky worlds, just the kind of object we’d like to eventually identify as an Earth 2.0. The problem seems to be wider than we have realized, given that about half of all stars exist in binary systems. New work has put some numbers on the problem. Conducted with data from the Gemini Observatory and the WIYN 3.5-meter telescope at Kitt Peak by NASA Ames researchers, the study examined TESS host stars using a...